Tunnel kiln



.ot.'12;192e. 1,602,721

' H. R. STRAIGHT TUNNEL KILN 'Filed Jan. 27, 192e 3 shegtsheet 1 VNTA/TW O ct. 12 1926.

H. R. STRAIGHT TUNNEL KILN :s sheets-sheet 2 Filed Jan. 27. 1926 /Wfffa/f H. R. 'STRAIGHT Oct. 12 1926.

TUNNEL KILN Filed Jan. 2'7. 1926 I5 Sheets-Sheet 5 Patented oct. 12, 1926.

HALvnn n. STRAIGHT, or ADEL, IOWA.

TUNNEL KILN.

Applicatie led ennery 27, 1 826. Serial No. 34,156.

This invention relates to a tunnel kiln for the burning of .ceramic Ware, and especially adapted for burning building materials and the like.

The object of my invention is to-prmide in a tunnel kiln in which the were Iis moved continuously `from the receiving `end to `the delivery end of ythe kilnim moved means vfor introducing the combustib e `materiel therei0 to.

A further object `is y-to provide -in u tunnel kiln ,improved means 'for imparting the proper circulation of air currents for the purpose Vof cooling the `were nl fter it has ntilizing-vthe'-hented eunrentsof air .for heat ing the were lzbefore it :reaches ;tl 1e.mu 'x1mum temperature zone.

A further ob'ect ,is to provide improved ineens lfor stile ingo/'the ware .on vthe kiln curs so that the cooling medium me' be moved through `the Iwere in a deling di' rection. .11. My invention. i consists in# the construction,

arrangement and combination ,offtle .YllZ-'i ons parts of the device, -gwherehy'thefob jects contem )lated yare attained, es#her-ein'` @after more ull set fox-th, pointedjoutf in I ny claimsen illustrated inthe-T acomam pnnying-drawngs, `inwwhich:

Figure 1 is :rplun vview ominiproved' kiln, a portionvof `the top lof It ebd'hing' V`zone beng'broken away.

' Figure 2 is e side-elevation offthe suine. Figure.' 3 1s u 'detailsegmental-sectional view taken. on thef line Figurejgl.

. Figure ,4T is .-u.V detml'gsegmentnl sectionlf view. teken on the lineA-.i ofligurel;

40 view tzil'ien on thelinefBQ-.ofgFigurefl- Figure (Sisy adetn'il sectionnl v iejw. taken' d'eleeting und retading 1nembers.

Figure 12 is a sectional view taken ou lthe y' line 12% 9 of' Figure. 2..

Figure 13 is a segmental sectional view taken on the line 155-13 of Figure A2.

Figure 14 is a segmental .sectional View teken Ion the line 14-14 yof `Fifglrlre 2.

Figure 15 is a. .segmentl *sectional v ew i 1 6 .arranged end ,to endtofrm n continuous' .tunnel AkilrL/ The Lsections .10; 1.1 and .12.11

fojrin' what s lmlltermtheehe'etin f ione of .whilefsection forms t e maximumjempereture zone, and section s-i14, 15,

und 16 forr'n `the eoolingzone. The esecfis provided with .truck .members Q17 which are Surrelfted ,0n suitable vtra,xisver'.Sly ur- .e'ng'ed beams .18; Whc'hjire' ,mounted in thetloor ofgthekiln. 1 hetrecks .17 are designed:ftosupportanlcarry a sereferably riesf of tunnel cnrs .19, seid eersllieifng provided withsupporting wheelsw 2,0.' The top .of xiehfobtheears 1.9 is provigled with a.

`floor 21 yformed .preferabl vof aseries 'of top 'of `the whatsimilanto that stkedythetl a.se riesl vof, vertical .passages of which y Each . made clear.

v march.l It willI beseenfiii Figures Extending longitudinally on the bottom of the kiln and at the outer sides of the tracks 17, I have provided an H-beam 26 secured to the members 18 by suitable brackets 27, said beams being placed in an in-VA clined position, as clearly shown in Figure 5, so that a groove 28 will be formed in the top surface of each of said beams. These grooves 28 are filled with sand 29, or similar material, and serve to form means for providing a seal betweenthe chamber below the cars and those on both sides of the cars. Each edge of each of the lcars is provided with a downwardly extending plate 30, the

lower edges of which extend into the sand 29. The cars 19 are run through the tun.- nel with their ends adjoining each other in such a manner that the warestacked thereon will form a substantially continuous column ofl Ware'. v`Means not illustrated in-the drawi "s is 'provided for im arting a `substantial y ,-continu'ous and s ow movement tosaid row oflbars; said means forming no part of my pre'seiitinvention.

' durable and In order to rovrdea cheap,

economical constructionjor each of the `kiln sections and at the Same time' providethe desired aircirculatio'; hereinafter to be described, throi`1g`h""-thefware vstacked on the cars,"I ha'vetorinedthe walls of each of said sections inttliefrm' o'f lthree arches, Which'I' shall 'termi the y'rniirr'arch 31, the ti -pass farch"""32 and" thedro'py arch 33.

e rbases "of YJtlie" main -`arch v"are" divergof andbe'lb'wit e top edge oat e said stack of Ware/l, YFi ure"13 shows in cross section the shape A on one end of the .Jmain arch, While" Figure 14"sliovvs"`in cross r-section the opposite end of" said' Imain' arch"I In Figure 13, it Will-be seen'that 'the base` ortionsl of the forwardu end ofthe' main are -31 of section 1G areyspread'apart a considerable distance from'thesides ofthe conveyor car, with the top portionof said archfollovving the contour of the topV of theware, softhat con'iparativelyl lar" e spacesA 34 are rovided at each side of' tie-ware, fwhilet ie space above"the..Ware atthis particular point is very much contracted. In Figure 14 the bases ofthe said arch are close to the sides of the kilnv car, while the to of the arch extends considerably above t e ware so a largespace" 35 is provided. 'Both ends of Asai 'archre formed circular. The center igure 13fis mia' lKt-)entrai vertical line iat a point terminatving inthe"by ass arch at a" ointbutside. farch 33 is at t considerably lower than the center of the arch section 14, in such a manner that in both sections of the arch the inner face of said arch is mounted close to the upper edge of the Walls 25, so that three distinct longitudinal compartments are formed, one above the Ware indicated by the numeral 35 andone at each side indicated by the numerals 34. The compartments 34 and 35 are brought into communication with each other circulating mechanism or fans 39, so arranged that the air will be delivered to the .compartments under pressure. i

Adjacent to the inner end of the arch 31 of section 16 is the byass arch 32, shown in section-in Figure" 17. n this arch it will be seen thatfa considerable space is provided :above the ware and at each side of the ware,

'and a ypassage 40 is. provided adjacent to the upper ends of the'walls 25, which causes the ycompartments above the ware and the compartments at the sides of the ware to be in communication. .,At. the inner end of the by-passarch 32 of section 16 is the drop arch 33,y which is clearly shownin Fi ure 15. This provides a. partition-between t e compartments 35 ofsection 16 and the compartments 35 ofsectionhl.

Between the inner, end ofthe arch 31 and `the outer end of., the arch 32 is a baille Wall 41, 1ocated adjacent to each side of the Ware so that adivisio'n is provided between the lcompartments 3ft/of` section 16 and the coin- Lpartments 34; of section 15. VIt should be noted that the baffle walls I41'are at the outer end of the bghpass `arch. while the drop e opposite end of the by-pass arch so that a current of'air moving longitudinally and inwardly. through the passage 35, will be moved downwardly between theside walls of the by-passvarch and the Walls 25 and into the passages 34 of section 15, in the manner herelnafter more vfully set .,forth. Sectionsl and 15 are similar in all respects to section 16 and no further description of these sections isv deemed necessary. l

Sections 10, 11 and 12 are also similar to the construction of section 16` with timex-` .fception that theyarearranged end toend and join onto section 13, forming 'the maximum temperature zone. This section 13 is also of arch .construction and is illustrated in section in Figure 1 6.` It will be seen that in said section considerablespace is provided at each side as well as abovelthe ware;y The uppery portion of said arch 13 provided with a series of laterally cand forwardlyfexf tending nozzles 42 arranged in tw groups Aand 4`extending inwardly and slightly down?" lOO wardly. Each of the nozzles 42 is flattened at its inner end, as clearly illustrated in` Figures 10 and 16. The nozzles of one group are in staggered relation with those ofthe other groop as viewed from above. The nozzles of each of said groups are connected to Vsuitable supply pipes 43, each of which is connected to a blower 44. Each of the supply pipes 43 is connected with a fuel through the ends of the passages 23, causing recirculation in the manner shown by the arrows in Figure 16. On account of the nozzles being slightly pointed forwardly,

'the tendency to create a forward movement of the` heated gases will also be maintained. In the practical operation of my device the ware is stacked on the cars 19 in the manl ner clearlyY illustrated in Figures 5 and6, with the upper portion of the stack of ware formed to substantially fit the under surface 0f the drop arches. The ware is fed into the left hand end of the kiln as illustrated in i l the Figures 1, 2, 3 and 4, and moved continuously through the kiln at a slow speed, and-the blowers 39 are operated as are also the blow` ers 44. Airis delivered to thepassages 34 iu section 16, whichfpasses lon itudinally of the ware and upwardly throug lthe stack through the passages 23 a-nd 24 into thecompartment 35, where it is moved longitudinally an'd inwardly above the ware in section-16, until it reaches the drop arch 32, Itis then moved downwardly between the walls of the by-pass arch and the walls 25 of the stack of ware', and'delivered into the compartment 34 of section 15, in' which case it is again* moved upwardly through the ware and again downwardly through I.the next bypass ,section and; again fupwardly through warelwin section, 14, .and williv be delivered directly in'to the co'mf artment v13 above the ware, where the fuel 1s inter-mingledv with the heated air from the cooling of the ware in sections 14, 15 ano.

16, at which time the heated gases will `pass downwardly through the ware Ain the com-j bustion'zone and a certain amount of rec1r` culation takes place, as previously described, so that the ware in this zone will become thoroughly heated. The g'ases then advance forwardly at a very slow speed and into enl, gagement with the drop arch 33 of section 12,

where they will be caused to pass under the ends of said drop arch into the by-pass arch 46. On account of the baille walls 41 of section 12, the gases will be moved upwardly through the compartment above the ware.

thence downwardly through the ware and into the compartments 34 ot said section into the bypass section 47 of section 11, and continning in this manner until they reach the end ot the kiln and pass outwardly through the stack 48 provided for that purpose.

B this arrangement it will be seen that.L

as t ie kware is advanced from the combusltion section 13, it vwillI gradually become w cooled as it is moved tothe delivery endof' said kiln. The air always moves upwardly through the ware, while passingk through the cooling zone, thereby providing means whereby the circulation of the air will be easily established, due to its natural tendency to rise as it is being heated.

It will -be seen, however,"that, as the air passes downwardly through the by-pass arches, it is working against'its natural tendency to rise. I have providedin each'of the passages in the by-pa'ss arch 32 of the cooling sections, a vertically-arranged radiation plate 49, clearly shown in Figure 9, or what `mightbe better termed a heat absorb-ing plate. The said plate is so arranged 4thata vertical passage 50 is provided, theupper` end-of which is connected to an air pipe 51 carried to the intake opening of `one of the fans 44.. The lower end of lthe passage"50 is provided with an opening 52 by means of whichai-r will be caused to enter the assage 50. .This air, bel ing from the outsidJ and' cooler than the cir .culating air within thekiln, will cause'the point to be downward. The late 49 serves toheat the air which is used; or combustion'V in` the lcombustion. chamber, thereby progid? ing. means for increasing the eiliciencyr of the `p1antas far as heating is concerned, as well as providing means whereby the ynatural circulation of t'heair through the kiln will be increased. y y

Ilhe gases passing-through the by-pass arches of the heating zone, n'amely'of sections 10. 11 and 12, will rise insteadzofiall,

inasmuch'as the gases are being cooled as they pass through this zone, and thervnat-V ural tendency is -to move downwardly as they pass through said by-pass arches. In order toV overcome this difficulty, I have provided inthe lower endfof the by-pass passages of said by-pass arches burners 54,

To overcomethis 'diliculty 7 sol lili) which will cause the gases to be heated .as

theyI pass upwardly through said passages, thereby overcoming the natural tendency of the gases to move downwardly through said assages on account of cooling off. Any

eat applied to the gases at this point serves to overcome the lossof heat, due to the cooling of the gases. The burnersg54 are provided with suitable supply pipes 55.

I have found by actual practice that a considerable advantage is gained by heating the ware quite rapidly for a certain period of time, and then permitting the ware to rest or soak for a certain period of time, then again rapidly increase the temperature and again permit the ware to pass through a soaking period.

I have also found advantage in cooling of the ware to provide certain soaking periods in which an even temperature is maintained for a certain period ottime. In order to accomplish these last results, I have utilized the by-pass arches of the sections of the` kiln in the following manner:

` In Figure 15, which is a section through one of these by-pass arches, I have illustratcd at the lower end of the by-pass passages fillers 56, which are of such height that their upper surfaces are vabove the passages 23, thereby serving to act as a valve for closing ysaid passages andto prevent any circula tion through the `ware as it passes through said by-pass arch, thereby permitting the ware to soak at whatever temperature happens to be while passing through the sai' arch. "The soaking, however, may be carried on at any desired temperature by simply increasing or decreasing the length of the section ori-,sections in front of the given 'oy-pass arch. That is, if the by-pass arch of section 15 is under consideration, then the temperature of the ware when passing through said arch may be determined by the temperature of the ware'as it passes from' the maximum temperature zone, the length of the section l 14 and the volume of cooling air passing through it. It will be seen that the temerature at this given section may be varied y either decreasing, or increasing the volume of air passing through the ware, or increas. `ing or decreasing the length of section 14.

After the proper length and volume ,have once been determined, the desired soaking temperatures at these by-pass arches may be easily maintained. It will be seen that any one of these by-pass sections may be converted into al soaking zone by simply filling the lower end of the by-p'ass passages to close the end of the passages 23.

f It will further be seen thatv` by constructl ing the main arches of each section .with their bases divergent, I have provided means whereby the sides of the passages 34 will be large at the intake end of said passagstand contracted at the opposite end, so t Vof the passages 35, I have also the...

gases will be forced quite uniformly horizontally through all of the passa es 23 of the given section. By increasing t e height of the arch at the delivery end of each section rovided means whereby this ,uniformity of t e velocity of the gases through the passa es 23 and 24 will be maintained, so that the eating or lcooling of the ware may be rapidlyaccom'- plished, and at 'an increasing or decreasing temperature from the burning zone to the disc arge end of the kiln, or from the burning zone to the intake end of the kiln.

I have found, however, in practice that gases moving longitudinally through the passages 34-establ1sh a certain amount of momentum, which causes the pressure of said gases to be increased near the baille walls 41, and the circulation through the passages 23` near these points to be increased. lThis difculty I have overcome by providing in the vertical walls of the arch members 31 of sections 14, 15 and 16 a series of retarding blocks 57, a perspective view of -whi'ehis shown in Figure 11. The blocks are s arranged that their inner ends project iritphe passages 34 a certain distance. Thefro'nt faces of the said blocks 57 are beveledbso that the bases are deflected inwardly towrd the ends of the passages 23. Said, blocks 5,7 are arranged in astaggered relation as shown in Figure'', so that t 1e longitudinal movement of the gases through the assages 34 is overcome to such an extent t at the momentum of sa'id gases will be brought to zero, thereby permitting a uniform velocity of the gases through the passages 23 and 24.

I have provided in the crown of the arches 31 of sections 10, 11 and 12, a similar arrangement of the blocks 57, said blocks being so arranged as to deflect the ases downwardly into the upper ends o the passages 24, thereby preventing the in creased pressure ofsaid gases a jacent to the drop arches 31. I

In` the drawings I have shown 'the walls 4of the tunnel kiln as a series of arches of is very common in kilns of this type'. Thisconstruction forms no part lof my present invention, and for that reason it has not been illustrated in the drawings. It will readily be seen that further structure would' be necessary in order to support arches of circular formation as illustrated herein.

It should be noted, however, that the arches 31 and 32I may be formed independently of each other, so that4 contraction and expansion joint maybe provided at the adjoining ends. of said" arches. ^..:The fd rop the arch 31 ot' tapered formation, I .have

provided means whereby air passa s of the desired shape may be easily an nquickly constructed; and on account-of being of an arch formation and properly supported by a suitahlewall construction ywhich includes proper insulation, I have provided a wall or deteriorating.

Thus it will be seen that I have provided a kiln `of simple, durable and inexpensive construetionyin which the temperature 'of the ware. may be rapidly increasedA or d e` creased without. cracking orlwar "ing fthe`l ware, and in lwhich any Vnumber o soaking zones may be established, andinwhiehthe circulation-fof the cooling orheating xriedii1`m` may he easily and'uniformly"maintained,

It will further' beseen that I"liavc"pro vided improved means for supplying c'ombustible materials to "the combustion zone and in such a manner that the circulation of the combustiblel `materials"through said zone is very uniformly maintained, andin which' the temperature of said 'zone maybe easilyregulated. V

It will further be seen that I` havey pro,4

vided im .rovedmeans whereby the moinen" e cireulatinggases maybe overs peratuie zone and a cooling zone, means lor deliveringr a coolingrmedium to the de` livery end of said kiln, ine-ans for delivering` the coolinginedium longitudinally along the sides ot the ware it passesrtlirough said kiln and througl'i said cooling zone,`aii .l'

means for moving said cooling medium transversely beneath ythe stack of* ware, thence upwardly through said ware, then f.lo\-.'nu'ar .li'y through the ware in said maximum temperature zone', and 4downwardly through the wnrcinv the heating zone.

In a tunnel kiln for burning ceramic wares, niears for supporting and moving ware to he liurned through said kiln compi'ising a heating zone, a maximum temperature zone und :i cooling zone, said heating zone and said cooling zone each being provided in a series ot intermediate sections,

means for introducing a cooling medium along the sides of tlieware in one of said cooling sections, Athen lhorlzontally beneath .the Vbottom of itlie ware and upwardly through it, .thence downwardly past-the sides of' Athefwarein the second section of said coolingzone, thence u wardly and again through the f ware, t ence downwardly through the ware in said'maximum temperature zone, thence upwardly past the side Vfto` the ytop in one of the sections of said construction which will withstand'a' larger variation in temperature without buckling heating zone, thence downwardly through the ware in said section, thence horizontally and outwardly and longitudinally and upwardl along the side of said wai-e to the top o the ware inthe secondsection of said heating zoneandr downwardly and outwardly as described.-

3L 4In,v a Atunnelkiln ,for :burning ceramic wares, meansrfor supporting and ymoving were -lto be burned'through saidkiln coinsoV prising -a heating zone, ,a maximum tem- `perature zone and a cooling zone, said heating zone and said vcooling zoneeach beingA provided Ain a series ofintermediate sections, means for introducing a cooling `medium along thegsidesof the ware in one of said `cooling,sections,then horizontally beneath thebottc of thc ware and upwardly 4through it, thence downwardly past the sides of theware in thelsecond sectionv of -said coolingizone, thence upwardly and through the ware of said second section, thence downwardlyA through the ware in 'said maximumtemperature zone, thence upwardlygto thcytop of theA ware in one of the sections of said heating zone, thence Adownwardly through the Ware in said section, thence' horizontally and outwardly and longitudinally along the sides of lsaid ware,

thence upwardly along the sides of the waieto the top ol the ware in the second section of said yheating zone and downwardly and foutwardl y `as before described, and means for preventing` the direetllow ot' the cooling or heating medium through the ware as it passes from one section to another section. y

4. In a tunnel kiln for bui-nino' ceramic wares, menus vl'or supporting an( moving ware to be burned through said kiln comprising a heating zone, iiiaxiinuni tenipei'uturc zone and a cooling' zone, said heat tions, iiieans for introducing a cooling,

nicdiuin along the sides ol' the ware in one ol' said cooling sections, then lunizoi'itally beneath the bottoni oi' the wai-'e and up- Wardly through it, thence downwardly to the sides ol' the 'are -in the second section of'said ,cooling zone, thence iip\v:|.rdly'and again through the ware, thence dou'i'iwardly through the ware in said inaxi'inuni temperature zone, thence upwardly to the top of the ware in one of the sections of said heating zone, thence downwardly through theware in said heating section, thence horizontally and outwardly and longitudinally along the sides of said ware, thenceupwardly along the sides of the ware to thel top of the ware in the second section of said heating zone and downwardly and outwardly as before described, and means for introducing a combustible material and air into the upper portion of said maximum temperature zone.

5. In a tunnel kiln lfor burning ceramic wares, means for supporting and moving ware to be burned through said kiln comprising a heating'zone, a maximum temperature zone and a cooling zone, said heating zone and said cooling zone each being provided in a series of intermediate sections, means for introducing a cooling medium along the sides of the ware in o ne of said cooling sections, then horizontally beneath the bottom of the ware and upwardly through it, thence downwardly to the sides of the ware in the second section of said cooling zone, thence upwardly and again through the ware, thence downwardly through the ware in said maximum temperature zone, thence upwardly to the top of the ware in one of the sectionsof said heating zone, thence downwardly through the ware in said section, thence horizontally and outwardly and longitudinally along the sides of said ware, thence upwardly along the sides of the ware to the top of the ware in the second section of said preheatino' zone and downwardly and outwardly as before i described, and means for introducing a combustible material and air" in to the upper portion ofsaid heating zone, the last said means being arranged in two groups, each of said groupscornprising a series of fuel introducing nozzles, the nozzles of one group being in staggered relation `with those of the other group, said nozzles' being inclined inwardly and downwardly.

f 6. In a tunnel kiln for burning ceramic wares, means for supporting and moving ware to be burned. through said kiln comprising a heating zone, a maximum temi perature zoneand a cooling zone, each of said heating and cooling zones being ldi-` vided into a series of intermediate zones, the spaces between the adjoining ends of the intermediate sections of said heating and cooling zones being provided with a by-pass section, each of the ley-pass sections` ,of said cooling zone being provided with cooling means, each of the by-pass sections of said heating zone beingprovided with heating means, the sections of said cooling zone being so arranged that the cooling medium will pass' upwardly through the ware as it passes through said zone and downwardly through said by-pass sections, the sections of said heating zone being arranged in such a manner that the heating medium will pass` downwardly through the ware i and up,

`wardly through said by-pass sections, and

means for introducing fuel' to said maximum temperature section.

7. lIn a tunnel kiln for burning ceramic wares, means forA supporting and moving ware to beburnedthrough said 1,kiln comprising a heating zone, a maximunntemperature zone and a cooling zone, each of said zones being divided into a series'ofiintermediate zones orsections, means for reducing the-temperature of the ware as it passes from the receiving end of said cooling zone to ythe delivery endA of said-zone, means forl of said ear being provided with a floor having transversely arranged grooves in its top surface, said grooves being opened at their endsfware to be burned being stacked on said floor in such a manner that vertical'passages will be formed, the sides of said stack of warebeingiled so as to provide a solid vertical wal the upper edges of said walls being designed to move in close 'proximity to the inner surface of said arch so that a longitudinal passage will be provided above the ware and one at Veach side of said ware, the passage above said ware being inl communication with the passages at the sideis of said ware through the horizontal ppassages of said door and thevertical passages of said ware.

9. In a tunnel kiln for burning ceramic wares, means for supporting and moving vare to be burned through said kiln comprising a heating zone, a maximum tempera- 4ture zone and a cooling zone, each of said cooling and heating zones being divided into a series of intermediate zones, the wall construction of each intermediate zone com,- prising a main arch, a by-pass arch and a drop arch, the bases of said main arch being arranged in a diverging manner relative to each other, the bases of said by-pass arch being substantially parallel the contracted ends of the base members of said main arch supporting an arch higher than the arch portion of the diverging ends of said main arch, the top of said drop arch bein of less curvature and lower than either of t e other two arches, said by-pass arch 'being of a height substantially equal to the highest point of the main arch and of a width subs o stacked that a passage will be lprovided longitdinally above the ware and a passage `longitudinally orf each side of the ware,

means for introducing and moving lthe coolmg or heating medium l longitudinally through one of said passages, and means for retarding' the' longitudinal movement of the cooling or heating'medium to counteract the momentum thereof and to deflect the medium transversely through the adjacent' passages of said ware.

- HALVER R. STRAIGHT. 

